Question
QUESTION: Hi Dr. Vann, I hope you can help save my boxwoods from leafminers :-)

Some of the leaves on my boxwoods have turned a tan colour. I did some research on the internet and discovered the problem is leafminers. Ideally I should have sprayed in the spring to prevent the adults from laying eggs but this first year I am seeing this problem so I will be on the lookout next spring. In the meantime, what can I do at this point to prevent more leaves from turning brown? Is it too late?

The boxwood also have the cupping leaves problem - psyllid. Again, I should have treated earlier but is there anything I can do now?

I think I have Green Mountain boxwoods - but not too sure about that.

Thanks for your expert help!
Debra



ANSWER: Deb:

Usually leafminers don't have much of an impact on the overall health of the plant.  You may wish to have your diagnosis confirmed. You can contact your local county Extension office or a reputable nursery/grenhouse in your community and arrange for someone there to look at a few affected leaves just to be sure.  A suitable example of an insecticide that can be applied to the soil is BAYER TREE AND SHRUB INSECTICIDE- it contains imidiachloripid, a systemic material taken up by the plant and is effective for many insects.

Steve

---------- FOLLOW-UP ----------

QUESTION: I pretty sure it's leafminer damage. I looked inside the leaves that are brown. There are no larvae or bugs inside so I think they have "left". Should I still use the insecticide to try to kill the dormant eggs??

Thanks!

Answer
Deb:
Initially, the immature(larvae) tunnel in between the upper and lower epidermis of the leaf blade- giving it a "squiggly" line appearance. The larvae mature into adult which emerges from tunnel.

The insecticide that I mentioned may be use- check on the label to be sure it is OK to use on boxwood and it is effective for LM. If only a few leaves are brown, consider puring a bit to remove before treating.

Steve